Genetics in oral-facial growth and diseases.

Much debate has taken place over the relative importance of heredity and environment in the development of various diseases and conditions. Dental problems are not often easily categorised into either genetic or environmental, because most anomalies involve the interaction of both factors. Since many genetic disorders involve the orofacial region, the importance of the subject is paramount in dentistry to enable a proper understanding of the development of the various conditions and the treatment of patients presenting with those conditions. The incidence of newborn children with any congenital anomaly is estimated to be as high as 2 to 3 per cent, with more than half of these abnormalities, including minor manifestations, found in the head and neck region. It is therefore not unusual for dentists to be the first to recognise such conditions in their patients and be responsible for providing the necessary treatment. This paper describes many conditions, genetically or partly genetically mediated, which affect the oro-facial tissues, and offers descriptions by which the clinician can start to identify those conditions.